Investigating the thermoelectric properties of p-type half-Heusler Hfx(ZrTi)1−xCoSb0.8Sn0.2 by reducing Hf concentration for power generation

Based on the fact that Hf is much more expensive than other commonly used elements in HfCoSb-based half-Heusler materials, we studied the thermoelectric properties of the p-type half-Heusler Hfx(ZrTi)1−xCoSb0.8Sn0.2 by reducing Hf concentration. A peak ZT of ∼1.0 was achieved at 700 °C with the composition of Hf0.19Zr0.76Ti0.05CoSb0.8Sn0.2 by keeping the Hf/Zr ratio at 1/4 and Hf/Ti at 4/1. This composition has much reduced cost and similar thermoelectric performance compared with our previously reported best p-type half-Heusler: Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. Due to the decreased usage of Hf, it is more favorable for consideration in applications. In addition, a higher output power is expected because of the higher power factor even though the conversion efficiency is the same due to the same ZT.